1. Field of The Invention
The invention relates to an optical coupler device, and particularly to the optical coupler having reinforcement structure on the fragile neck portion for efficiently resisting any exterior influence.
2. The Related Art
The optical coupler are popularly used in an optical transmission system. As well known and shown in FIG. 1, the typical coupler 10 includes a pair of generally mutually parallel optical fibers 12 extending through a tubular enclosure 14 wherein each optical fiber 12 has an axial core portion 15 extending therethrough in the center thereof for allowing the light to move therein. The middle portions 16 of such pair of optical fibers 12 deformably move toward each other in a very close manner and form a hourglass sectional configuration in the enclosure 14 whereby the light moving along one fiber 12 may transmit to the adjacent fiber 12 around the neck portion 18 (i.e., the active area) of aforementioned hourglass configuration. This is because the core portion 15 of the one fiber 12 becomes much closer to that of the other and the light can easily leak or jump to another adjacent fiber 12. Interchangeability of the light between such two fibers defines coupling function of the light transmission, and this is the reason why the coupler is so called.
The typical method to make the hourglass-like configuration of the fiber assembly in the coupler is described below. First, two ends of the such pairs of side-by-side fibers 12 are held by suction device, and simultaneously oppositely and outwardly pulling forces are applied to two opposite ends of each fiber 12 to have both fibers in a tension status. Successively, a torch or other heat source is applied to the middle portions of the closely parallel fibers 12 to soften such specific positions thereof. Therefore, the fibers around such heated area may become narrower or thinner, and such area naturally becomes a neck portion 18 of a hourglass-like configuration. Under this situation, the inner core portion 15 of such pair of fibers 12 are moved much closer to each other as shown in FIG. 1, thus facilitating implementation of the coupling performance thereabouts. It can be understood that the closer these two fibers 12 are with each other, the higher the percentage of interchangeability of the transmitted lights. Anyhow, there is a limitation regard the dimension of such neck portion 18 wherein the maximum limitation should meet the minimum interchangeability ratio between such pair of fibers 12, and the minimum limitation should own the desired strength to resist the structure fatigue due to any external impact or vibration. Nevertheless, for achievement of better coupling effect, most coupler manufacturers can not help but make the neck portion 18 with a dimension of the critical value around such minimum limitation. Under this situation, such coupler 10 is so fragile and sensitive in comparison with other fiber optics components from a mechanical viewpoint. Any server vibration or improper impact, or falling on or of the coupler 10 results in large, relative to the tiny neck portion, external forces and inertia forces, and may cause breaking around the neck portion 18 of the fibers 12. This unavoidable issue results in high difficult and complexity and high defective ratio for the manufacturer. Understandably, there is really a desire to obtain a coupler having not only a required optical coupling performance to implement the designated purpose, but also a sufficient strength to allow practical and reliable usage of the product.
Therefore, an object of the invention is to provide a coupler and the method making the same wherein a reinforcement means is applied to the coupler so that the coupler may have a better mechanical property and allow larger tolerance during manufacturing.